Highloft needlepunched nonwovens

ABSTRACT

The present disclosure relates to a highloft needlepunched fabric wherein said fabric may be formed by needlepunching a web at a penetration density of less than or equal to about 150 penetrations per square centimeter and a penetration depth of about 5-20 mm, wherein the needles are spaced apart 5 mm or greater.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 60/869,637, filed Dec. 12, 2006, the teachings of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to a highloft needlepunched nonwoven and the formation thereof.

BACKGROUND

Nonwoven fabrics have found a variety of applications. For example, various nonwoven fabrics have been utilized in consumer applications, such as mattresses and bedding, where the fabrics must meet state and federal performance standards, such as California Technical Bulletin 603 or flammability standard 16 CFR 1633, which will become effective on Jul. 1, 2007. Accordingly, various flame retardant blends have been utilized in different components of the mattress, i.e. the mattress top panel or side borders, to meet these standards. For example, a flame resistant (FR) highloft, which may be thermally bonded, has been included as one of the outer layers of the mattress under the mattress ticking. However, highloft materials may create a relatively firmer feel to the mattress.

Siliconized fibers have been utilized in FR blends, such as those used in highloft materials, to overcome the relatively firmer feel created by the FR materials. In particular, siliconized fibers have been utilized in those blends that include FR cellulosic materials (both inherently FR and post treated). However, the siliconized fibers may increase the flammability of the materials.

In addition, relatively thin needlepunched products have been utilized which may meet the various standards set for both on the state and federal level. Yet, due to the thickness these materials, they do not exhibit the desired quilted “pop” or variation in thickness between quilted (i.e. sewn or bonded) and un-quilted areas.

SUMMARY

The present disclosure contemplates a method of needlepunching material to form a fabric. The method may include forming a web and penetrating the web with a plurality of needles, at a penetration density less than or equal to about 150 penetrations per square centimeter and a penetration depth of about 5-20 mm, wherein the needles may be spaced apart 5 mm or greater.

BRIEF DESCRIPTION OF DRAWINGS

The detailed description below may be better understood with reference to the accompanying figures which are provided for illustrative purposes and are not to be considered as limiting any aspect of the invention.

FIG. 1 is an illustration of an exemplary needlepunching process;

FIG. 2 is perspective view of an embodiment of an exemplary needleboard; and

FIG. 3 is a top view of a needle board including rows of offset needles.

DETAILED DESCRIPTION

The present disclosure relates to needlepunching a highloft nonwoven material. Needlepunching generally refers to a process which mechanically entangles fibers to produce nonwoven fabrics. Generally, the process may include mechanically binding a web to form a fabric by penetrating the web with an array of barbed needles that carry tufts of the web's own fibers in a vertical direction through the web. For example, the process may utilize a needleboard capable of producing about 250-700 penetrations per square centimeter, wherein the needle boards may include about 16000 needles per board and the spacing of the needles in the needle boards may be in the range of about 3 to 4 mm in each direction. However, retention of loft has been relatively difficult to achieve.

Contemplated herein is a relatively highloft needlepunched fabric that has a basis weight in the range of about 100 to 800 grams per square meter (g/m²), including all values and increments therein, such as 230 g/m², 290 g/m², 360 g/m², etc. The product may have a thickness of greater than 5 mm, and for example between about 5 to 30 mm, including all values and increments therein, such as 9 mm, 12 mm and 14 mm.

In addition, the product may have a tensile strength below about 20 pounds per 2 inch (lbs/2″). As one example, for a 290 g/m² product, the tensile strength may be about 8 lbs/2″. Furthermore, the product may have a tensile strength in the machine direction in the range of 1 to 15 (lbs/2″), including all increments and values therein and a tensile strength in the cross machine direction in the range of 5 to 20 lbs/2″, including all increments and values therein.

The product may be further characterized as having a char-strength, that is the tensile strength after exposure to flame pursuant to 16 CFR 1633, in the range of 0.5 to 5 lbs/2″ at about 6.5% elongation, including all values and increments. For example, a tensile strength of about 1.5 lbs/2″, 2.5 lbs/2″, etc.

The needlepunched product may utilize a variety of fiber materials, such as synthetic materials or non-synthetic materials. Exemplary fibers may include nylon, acrylic, modacrylic, aramids, polyester, melamine, melamine/formaldehyde fibers, olefins including polyethylene or polypropylene, polylactic acid, acetate, triacetate, rayon, cellulose, cotton, lyocell, wool, etc. The fibers may also be FR treated or modified to become FR fibers. Binder materials, such as binder fibers and or a binder layer may also be incorporated into the products contemplated herein. Additionally, inorganic fillers may be used to coat or saturate the products contemplated herein, providing additional fire blocking characteristics.

In particular, modacrylic fiber may be based upon a polyacrylonitrile copolymer with a halogen containing comonomer. The halogen containing comonomer may include for example poly(vinyl chloride) or poly(vinylidine chloride). An exemplary modacrylic fiber is available form Kaneka Corporation, under the trade name Kanecaron™ Protex. In particular, the modacrylic employed herein is sold under the trade name Kanecaron™ Protex PBX, at a specific gravity of 1.45-1.60 with a fiber denier of 2.2 dtex×38 mm. Protex PBX is described as having the following chemical components: acrylonitrile, vinylidine chloride copolymer, antimony oxide. An exemplary melamine/formaldehyde fiber component is sold under the trade name Basofil™, available from McKinnon-Land-Moran, LLC.

Cellulosic fiber is a general reference to a viscose or regenerated cellulose fiber as well as natural cellulosic fibers. Viscose fiber is a general reference to a fiber produced by the viscose process in which cellulose is chemically converted into a compound for ultimate formation into a fiber material. An exemplary viscose containing silicic acid is sold under the trade name FR Corona, available from Daiwabo Japan, or Visil™, available from Sateri Oy Inc. The Visil fiber may be type AP 33 3.5 dtex×50 mm. It is composed of 65-75% regenerated cellulose, 25-35% silicic acid, and 2-5% aluminum hydroxide.

Regenerated cellulose is general reference to cellulose that is first converted into a form suitable for fiber preparation (e.g. xanthation) and regenerating the cellulose into fiber form. The regenerated cellulose fiber may be prepared from wood pulp. Lyocell fiber is broadly defined herein as one example of a synthetic fiber produced from cellulosic substances. Lyocell is reportedly obtained by placing raw cellulose in an amine oxide solvent, the solution is filtered, extruded into an aqueous bath of dilute amine oxide, and coagulated into fiber form. From a property perspective, lyocell is also described as being a relatively soft, strong and absorbent fiber, with excellent wet strength, that happens to be wrinkle resistance, dyable to a number of colors, simulating silk or suede, with good drapability. Natural cellulosic fibers may include, e.g., cotton, ramie, kenaf, flax, etc.

The fibers herein (e.g., natural cellulose or regenerated cellulose) may be treated with a fire retardant additive, such as a phosphorous compound or a halogen compound or an antimony compound. Exemplary phosphorous compounds include organic phosphates, phosphoric acid esters, and quaternary phosphonium compounds. It may also be appreciated that the level of any such fire retardant additive may be in the range of 5-30% by weight with respect to a given fiber, including all values and ranges therein. For example, one particularly useful range of fire retardant additive may be between about 10-15% by weight. Furthermore, with respect to the actual treatment of the fibers herein with such fire retardant additive, it may be appreciated that the additive may be applied to a fiber alone (e.g., to the natural cellulose fiber or viscose fiber) or even to the web that may ultimately contain the cellulose fiber in combination with other fiber components.

Aramid fiber is reference to an aromatic polyamide type fiber material, such as a poly (p-phenylene terephthalamide) made by E.I. DuPont de Nemours & Co. and sold as KEVLAR®. Aramid fiber may also be a reference to an aromatic polyamide type fiber material, such as poly (m-phenyl terephthalamide) made by E.I. DuPont de Nemours & Co., sold number the trade name Nomex®. Aramid fiber may also be available from Teijin under the trade name Twaron™.

The binder may include polymer binder fiber incorporated in the layers of the non-woven textile or added as a layer in between layers of materials described herein. The binder may be in the form of a powder, web, or fibers. Fibers may be in the form of a sheath/core, side-by-side, or monofilament configuration.

The binder fibers of the present invention may include one or a plurality of polymer components. Binder fibers may be, for example, 4d×2″ from either Nan Ya or Sam Yang in Korea with the outer layer having a melting point of 150° C. which melting point is lower than the melting point of the inner layer of this particular binder fiber material. The binder fiber outer layer may melt and flow onto the other fibers which bond the structure together.

Inorganic fillers may be included as a coating on the fabrics or in individual fabric layers. Inorganic fillers may include, for example, vermiculite, graphite, fumed silica or silica dioxide, or titanium dioxide, and mixtures thereof. Vermiculite, for example, is reference to one of the mica groups that may be used as granular fillers, and comprises a crystalline layer silicate material. However, some of the silicon atoms may be replaced with aluminum, producing a negative charge that is neutralized by the interlayer cations, mostly magnesium. The vermiculite particles may be of a planar structure consisting of platelets that have a minimum 400:1 xy plane to z plane ratio. The level of vermiculite herein, as a coating in the fabric, is about 20-40 g/m², including all increments therebetween at 1.0 g/m² variation.

The fibers described above, may be used in combination and may be formed into one or more layers. In an exemplary embodiment a FR rayon may be present in the product in the range of about 20 to 100% by weight, including all values and increments therein, such as 50 to 80% by weight. In addition, a modacrylic FR may be present in the product the range of about 0 to 100% by weight, including all values and increments therein such as 0 to 40% by weight. Furthermore polyester fiber, which may include mono-component, bi-component, binder fiber, FR, combinations thereof, may be present in the product in the range of about 0 to 100% as well including all increments and values therein, such as 0 to 70% by weight.

The fibers described above may be provided in a web. The web may be spunbond or carded. However, other web forming processes are contemplated as well, such as airlaid webs, melt blown webs, etc. More than one web may be assembled and needlepunched as provided herein.

A person of ordinary skill in the art would recognize, as illustrated in FIG. 1, that a needlepunching apparatus 10 may generally include providing a web of fibers 12 which may pass underneath a number of barbed needles 14 affixed to a needle board 16. The apparatus 10 may also include a stripper plate 18 and a bed plate 20. The needles may therefore, pass through the stripper plate 18, through the web 12 and into the bed plate 20. The stripper plate and/or bed plate may include a number of holes through which the needles may pass through. As the needles pass through the web, they may carry tufts of fiber through the web, interlocking the fibers into a fabric.

Accordingly, to achieve the fabric products contemplated herein, the needle boards may include in the range of about 1,000 to 5,000 needles per board, including all values and increments therein. In addition, as illustrated in FIG. 2 the needles may specifically be spaced apart a given dimension “A”, wherein “A” may be in the range of greater than about 5 mm, and more specifically about 8 to 20 mm, including all values and increments therein, such as 13 mm, 14 mm, etc. Furthermore, it may be appreciated that the number of needle lines in the machine direction “MD” may also be reduced or limited and may be spaced apart a given dimension “B”, wherein “B” may be in the range of greater than about 5 mm. In addition, the spacing as between A and B may be such that they are either equal or differing quantities. For example, dimension A may be about 13 mm and dimension B may be about 15 mm.

As illustrated in FIG. 3, it is also contemplated that with a given needle row 32 mounted on the needle board 30, the needles 34 may be offset in the machine direction in a given dimension “C” from each other, wherein “C” may be in the range of about 1 to 8 mm, including all values and increments therein. This then may create a row of needles that are not necessarily aligned perpendicular to the machine direction and may form a selected angle other than 90 degrees. In addition, as illustrated in FIG. 3, as the row of needles proceeds in the cross machine direction, the needles may be non-linear.

The needles used herein may include standard needles of 15×18×38 CB22. However, other needles may be utilized as well. For example, the needle gauge may be in the range of about 12 to 50, including all values and increments therein. In addition various crank, shank, blade, barb and point geometries may be utilized as well.

The needle machine may use only one needle board in the machine direction containing the above referenced quantity and geometry (e.g. non-linear pattern) of needles. Accordingly, the fabric products herein may therefore be formed via a needlepunching process wherein the fabrics may have a penetration density of less than 150 penetrations per square centimeter, including all values and increments therein, such as 40 to 50 penetrations per square centimeter. The material may also be needled from only one side.

However needling from both sides is contemplated herein as well, wherein either the top or bottom of the web may be individually penetrated at a penetration density in the range of less than or equal to about 150 penetrations per square centimeter, e.g. about 20 to 95 penetrations per square centimeter, including all values and increments therein. It is also contemplated that the number of penetrations on a first side may be the same or different than the number of penetrations as a second side. For example, a first side may have a penetration density of about 45-penetrations per square centimeter and the second side may have a penetration density of about 20 penetrations per square centimeter.

In addition, the penetration depth may be varied. The penetration depth may be in the range of 5-20 and the depth may also be the same per side, or different per side. For example, when penetrating the web from only one side, the needles may penetrate a depth in the range of about 5 to 20 mm, including all increments and values therein. When penetrating the web from both sides, the needles may penetrate at a depth in the range of about 2 to 10 mm, including all increments and values therein. Accordingly, it should be understood that when penetrating the web from both sides, the penetration depth of one side may be a certain percentage of the depth of penetration of the other side, wherein such percentage may be in the range of 1-99%.

Furthermore, one may alter the needleboard configuration so as to create visible patterns in the product surface. It should also be appreciated that other variables such as speed, revolution rate and penetration depth could also be varied to create distinctive patterns.

Accordingly, provided herein is a material that may have a softer hand and may be relatively less stiff than thermally bonded fabrics as well as other needlepunched products. One technique to evaluate softness may therefore rely upon a side by side comparison of informed observers so as to statistically differentiate the reported softness of the present needlepunched product versus other products. For example, the softness of the needlepunched product herein was evaluated relative to thermally bonded products and other needlepunched products. Such needlepunched products had at least 25% air by volume, a basis weight of 310 g/m² and a thickness of 13 mm and were needlepunched from only one direction. The needlepunched materials herein were identified as softer than such products.

Furthermore, to determine the performance of the products formed by the process discussed herein in an actual mattress application, the needlepunched fabric herein having a basis weight of about 300 g/m² and a thickness of 12 mm was used to construct a mattress in the top and panel sections. In addition, other fabrics that were thermally bonded having a basis weight of about 230 g/m² and a thickness of 13 mm, and those that were needlepunched and had at least 25% air by volume, a basis weight of 310 g/m² and a thickness of 13 mm and were needlepunched from only one direction, were used for comparison to construct the top and side panels of mattresses. The mattresses were tested by observers evaluating the panel sides of the mattresses and lying on the beds constructed with the fabrics. The result was that the thermally bonded materials felt firm and stiff. In addition, the needlepunched material having at least 25% air by volume, a basis weight of 310 g/m² and a thickness of 13 mm and were needlepunched from only one direction, was again reported as less soft than the needlepunched products disclosed herein.

The foregoing description is provided to illustrate and explain the present invention. However, the description hereinabove should not be considered to limit the scope of the invention set forth in the claims appended here to. 

1. A method of needlepunching material to form a fabric comprising: forming a web; and penetrating said web with a plurality of needles, at a penetration density less than or equal to about 150 penetrations per square centimeter, a penetration depth of about 5-20 mm, and wherein said needles are spaced apart 5 mm or greater.
 2. The method of claim 1 wherein said plurality of needles are mounted on a needle board at a spacing in the range of about 8 to 20 mm.
 3. The method of claim 1 wherein said needles define at least one row and said needles in a given row are offset from one another about 1-8 mm in a machine direction.
 4. The method of claim 1 wherein said plurality of needles are mounted on a needle board, wherein the needle board includes in the range of about 1,000 to 5,000 needles.
 5. The method of claim 1 wherein said web includes a first surface and a second surface and only said first surface is penetrated with said plurality of needles.
 6. The method of claim 1 wherein said web includes a first surface and a second surface, and said penetration depth of said needles is different in said first surface as compared to said second surface.
 7. The method of claim 1 wherein said web includes a first surface and a second surface and said penetration density of said first surface is different than said penetration density of said second surface. 